Intermediates for preparing amino thiol dipeptides

ABSTRACT

Intermediates of the formula ##STR1## are disclosed. These compounds are useful in the preparation of amino thiol dipeptides possessing angiotensin converting enzyme inhibition activity and enkephalinase inhibition activity.

This is a division of application Ser. No. 602,030, filed Apr. 19, 1984.

BACKGROUND OF THE INVENTION

Natarajan et al. in Belgian Pat. No. 897,327 disclose amino ketonedipeptides of the formula ##STR2## wherein R₁ is hydrogen only when R isother than hydrogen.

Gordon et al. in U.S. Ser. No. 515,729 filed July 21, 1983 disclosehydroxy substituted dipeptides of the formula ##STR3## which areprepared by treating the corresponding keto compound with a reducingagent.

Meyer et al., "Angiotensin Converting Enzyme Inhibitors:Modifications OfA Tripeptide Analogue", J.Med.Chem., 1982, 25, 996-999, disclose thesynthesis and angiotensin converting enzyme inhibition activity ofcompounds of the formula ##STR4## wherein X can be NH and R can beL-proline.

Almquist et al. in U.S. Pat. No. 4,329,473 disclose oxoalkanoic acidderivatives of L-proline as angiotensin converting enzyme inhibitors.

SUMMARY OF THE INVENTION

This invention is directed to the amino thiol dipeptide compounds offormula I and salts thereof ##STR5##

X is an amino or imino acid of the formula ##STR6##

n is zero, one, or two.

R₂₅ is lower alkyl of 1 to 4 carbons or ##STR7##

R₇ is hydrogen, lower alkyl, halogen, hydroxy, ##STR8## a 1- or2-naphthyl of the formula ##STR9## --(CH₂)_(m) --cycloalkyl, ##STR10##--O--lower alkyl, ##STR11## a 1- or 2-naphthyloxy of the formula##STR12## --S--lower alkyl, ##STR13## or a 1- or 2-naphthylthio of theformula ##STR14##

R₈ is halogen, ##STR15## --O--lower alkyl, a 1- or 2-naphthyloxy of theformula ##STR16## --S--lower alkyl, ##STR17## or a 1- or 2-naphthylthioof the formula ##STR18##

R₉ is keto or ##STR19##

R₁₀ is halogen or --Y--R₁₆.

R₁₁, R'₁₁, R₁₂ and R'₁₂ are independently selected from hydrogen andlower alkyl or R'₁₁, R₁₂ and R'₁₂ are hydrogen and R₁₁ is ##STR20##

R₁₃ is hydrogen, lower alkyl of 1 to 4 carbons, lower alkoxy of 1 to 4carbons, lower alkylthio of 1 to 4 carbons, chloro, bromo, fluoro,trifluoromethyl, hydroxy, phenyl, phenoxy, phenylthio, or phenylmethyl.

R₁₄ is hydrogen, lower alkyl of 1 to 4 carbons, lower alkoxy of 1 to 4carbons, lower alkylthio of 1 to 4 carbons, chloro, bromo, fluoro,trifluoromethyl, or hydroxy.

m is zero, one, two, three, or four.

p is one, two or three provided that p is more than one only if R₁₃ orR₁₄ is hydrogen, methyl, methoxy, chloro, or fluoro.

R₁₅ is hydrogen or lower alkyl of 1 to 4 carbons.

Y is oxygen or sulfur.

R₁₆ is lower alkyl of 1 to 4 carbons, ##STR21## or the R₁₆ groups jointo complete an unsubstituted 5- or 6-membered ring or said ring in whichone or more of the carbons has a lower alkyl of 1 to 4 carbons or adi(lower alkyl of 1 to 4 carbons) substituent.

R₄ is hydrogen, lower alkyl, ##STR22##

R₅ is hydrogen, lower alkyl, ##STR23## --(CH₂)_(r) --NH₂, --(CH₂)_(r)--SH, --(CH₂)_(r) --S--lower alkyl, ##STR24##

r is an integer from 1 to 4.

R₁₉ is lower alkyl, benzyl, or phenethyl.

R₂₀ is hydrogen, lower alkyl, benzyl or phenethyl.

R is hydrogen, lower alkyl, cycloalkyl, ##STR25## --(CH₂)₂ --NH₂,--(CH₂)₃ --NH₂, --(CH₂)₄ --NH₂, --(CH₂)₂ --OH, --(CH₂)₃ --OH, --(CH₂)₄--OH, --(CH₂)₂ --SH, --(CH₂)₃ --SH, or --(CH₂)₄ --SH.

R₁ is hydrogen, lower alkyl, halo substituted lower alkyl, ##STR26##--(CH₂)_(r) --NH₂, --(CH₂)_(r) --SH, --(CH₂)_(r) --OH, --(CH₂)_(r)--S--lower alkyl, --(CH₂)₂ --S--(CH₂)₂ --NH₂, ##STR27##

R₂ is ##STR28##

R₃ is hydrogen, lower alkyl, ##STR29## halo substituted lower alkyl,--(CH₂)_(m) -cycloalkyl, ##STR30## --(CH₂)_(r) --NH₂, --(CH₂)_(r) --SH,--(CH₂)_(r) --S--lower alkyl, ##STR31## wherein m, R₁₄, p and r are asdefined above.

R₆ is hydrogen, lower alkyl,p-methoxybenzyl,benzhydryl, ##STR32##--CH--(CH₂ --OH)₂, ##STR33## --(CH₂)₂ --N(CH₃)₂ or ##STR34##

R₁₇ is hydrogen, lower alkyl, cycloalkyl, or phenyl.

R₁₈ is hydrogen, lower alkyl, lower alkoxy, or phenyl or R₁₇ and R₁₈taken together are --(CH₂)₂ --, --(CH₂)₃ --, --CH═CH--, or ##STR35##

R₂₁ and R₂₂ are independently selected from hydrogen and lower alkyl.

R₂₃ is lower alkyl.

R₂₄ is hydrogen, lower alkyl, ##STR36##

DETAILED DESCRIPTION OF THE INVENTION

This invention in its broadest aspects relates to the amino thioldipeptide compounds of formula I above, intermediates useful in thepreparation of such compounds, compositions containing such compoundsand the method of using such compounds as pharmaceutical agents.

The term lower alkyl used in defining various symbols refers to straightor branched chain radicals having up to seven carbons. The preferredlower alkyl groups are up to four carbons with methyl and ethyl mostpreferred Similarly the terms lower alkoxy and lower alkylthio refer tosuch lower alkyl groups attached to an oxygen or sulfur.

The term cycloalkyl refers to saturated rings of 3 to 7 carbon atomswith cyclopentyl and cyclohexyl being most preferred.

The term halogen refers to chloro, bromo and fluoro.

The term halo substituted lower alkyl refers to such lower alkyl groupsdescribed above in which one or more hydrogens have been replaced bychloro, bromo or fluoro groups such as trifluoromethyl, which ispreferred, pentafluoroethyl, 2,2,2-trichloroethyl, chloromethyl,bromomethyl, etc. The symbols ##STR37## represent that the alkylenebridge is attached to an available carbon atom.

The compounds of formula I can be prepared according to the followingprocedure. An aldehyde of the formula ##STR38## is reductively coupledwith a dipeptide ester of the formula ##STR39## wherein R₆ in thedefinition of X is an acid cleavable protecting group such as t-butyl,benzhydryl, or p-methoxybenzyl.

The resulting p-methoxybenzyl protected compound of the formula##STR40## is treated with trifluoroacetic acid and anisole to remove theR₆ ester group and mercuric trifluoroacetate acid to remove thep-methoxybenzyl sulfur protecting group and give the amino thiol productof formula I.

The aldehyde intermediate of formula II can be prepared as follows. AnN-protected carboxylic acid of the formula ##STR41## wherein prot is aprotecting group such as benzyloxycarbonyl is treated with diazomethanein the presence of N-methylmorpholine and isobutylchloroformate to yield##STR42##

The diazo compound of formula VI in methanol is treated with silverbenzoate and triethylamine to yield the methyl ester of the formula##STR43## Removal of the N-protecting group such as by hydrogenationfollowed by reaction with the acid chloride of the formula ##STR44##yields the methyl ester of the formula ##STR45##

The methyl ester of formula IX is treated with lithium diisopropylamineand the disulfide of the formula ##STR46## at low temperature to yieldthe protected sulfide of the formula ##STR47##

The methyl ester of formula XI is treated with lithium chloride andsodium borohydride to yield the alcohol of the formula ##STR48## Thealcohol of formula XII is treated with pyridinium-1-sulfonate anddimethylsulfoxide in the presence of diisopropylethylamine to yield thealdehyde of formula II.

The dipeptides of formula III are described in the literature. They canbe obtained by reacting the N-protected amino acid of the formula##STR49## wherein the N-protecting group is benzyloxycarbonyl,t-butoxycarbonyl, or p-methoxybenzyloxycarbonyl with the imino or aminoacid ester of the formula

    H--X                                                       (XIV)

Removal of the N-protecting group yields the intermediate of formulaIII. When the imino or amino acid of formula XIV is known in the acidform it can be readily converted to the ester by conventional means. Forexample, the esters where R₆ is t-butyl can be obtained by treating thecorresponding N-carbobenzyloxy imino or amino acid with isobutyleneunder acidic conditions and then removing the N-carbobenzyloxyprotecting group by catalytic hydrogenation.

In the above reactions if any or all of R, R₁, R₃ and R₅ are ##STR50##--(CH₂)_(r) --SH, --(CH₂)_(r) --OH, or ##STR51## then the hydroxyl,amino, imidazolyl, mercaptan or guanidinyl function should be protectedduring the reaction. Suitable protecting groups includebenzyloxycarbonyl, t-butoxycarbonyl, benzyl, benzhydryl, trityl, etc.,and nitro in the case of guanidinyl. The protecting group is removed byhydrogenation, treatment with acid, or other known methods followingcompletion of the reaction.

The ester products of formula I wherein R₆ is ##STR52## may be obtainedby employing the dipeptide of formula III in the above reactions withsuch ester group already in place. Such ester reactants can be preparedby treating the dipeptide of formula III wherein R₆ is hydrogen with anacid chloride such as ##STR53## so as to protect the N-atom. Theprotected compound is then reacted in the presence of a base with acompound of formula ##STR54## wherein L is a leaving group such aschlorine, bromine, tolylsulfonyl, etc., followed by removal of theN-protecting group such as by treatment with acid or hydrogenation.

The ester products of formula I wherein R₆ is ##STR55## can also beobtained by treating the product of formula I wherein R₆ is hydrogenwith a molar excess of the compound of formula XV.

The ester products of formula I wherein R₆ is ##STR56## can be preparedby treating the product of formula I wherein R₆ is hydrogen with a molarexcess of the compound of the formula ##STR57##

The ester products of formula I wherein R₆ is --CH--(CH₂ --OH)₂ or##STR58## can be prepared by coupling the product of formula I whereinR₆ is hydrogen with a molar excess of the compound of the formula##STR59## or the formula ##STR60## in the presence of a coupling agentsuch as dicyclohexylcarbodiimide followed by removal of the hydroxylprotecting groups.

Similarly, the ester products of formula I wherein R₆ is --(CH₂)₂--N(CH₃)₂ or ##STR61## can be prepared by coupling the product offormula I wherein R₆ is hydrogen with a molar excess of the compound ofthe formula

    HO--CH.sub.2 --CH.sub.2 --N--(CH.sub.3).sub.2              (XIX)

or the formula ##STR62## in the presence of a coupling agent such asdicyclohexylcarbodiimide.

The products of formula I wherein R₇ is amino may be obtained byreducing the corresponding products of formula I wherein R₇ is azido.

Preferred compounds of this invention with respect to the peptide partof the structure of formula I are those wherein:

R is hydrogen or straight or branched chain lower alkyl of 1 to 4carbons.

R₁ is hydrogen, straight or branched chain lower alkyl or 1 to 4carbons, --CF₃, --(CH₂)_(r) --NH₂ wherein r is an integer from 1 to 4,##STR63## --CH₂ --SH, --(CH₂)₂ --S--(CH₂)₂ --NH₂, --(CH₂)₂ --S--CH₃,##STR64## --CH₂ --OH, ##STR65##

R₄ is hydrogen, cyclohexyl or phenyl.

R₅ is hydrogen, straight or branched chain lower alkyl of 1 to 4carbons, --CH₂ OH, ##STR66## --(CH₂)₄ --NH₂, --CH₂ --SH, --(CH₂)₂--S--CH_(3l) , ##STR67##

R₆ is hydrogen, straight or branched chain lower alkyl of 1 to 4carbons, alkali metal salt, ##STR68## --CH--(CH₂ --OH)₂, ##STR69##

r is an integer from 1 to 4.

R₂₃ is straight or branched chain lower alkyl of 1 to 4 carbons,especially --C(CH_(3l) )₃.

R₁₇ is hydrogen, straight or branched chain lower alkyl of 1 to 4carbons, or cyclohexyl.

R₁₈ is straight or branched chain lower alkyl of 1 to 4 carbons orphenyl.

R₇ is hydrogen.

R₇ is hydroxy.

R₇ is straight or branched chain lower alkyl of 1 to 4 carbons orcyclohexyl.

R₇ is amino.

R₇ is --O--lower alkyl wherein lower alkyl is straight or branched chainof 1 to 4 carbons.

R₇ is ##STR70## wherein m is zero, one or two and R₁₃ is hydrogen,methyl, methoxy, methylthio, chloro, bromo, fluoro, or hydroxy.

R₇ is ##STR71## 1-naphthyloxy or 2-naphthyloxy wherein m is zero, one,or two and R₁₃ is hydrogen, methyl, methoxy, methylthio, chloro, bromo,fluoro, or hydroxy.

R₇ is --S--lower alkyl wherein lower alkyl is straight or branched chainof 1 to 4 carbons.

R₇ is ##STR72## 1-naphthylthio, or 2-naphthylthio wherein m is zero,one, or two and R₁₃ is hydrogen, methyl, methoxy, methylthio, chloro,bromo, fluoro, or hydroxy.

R₈ is --O--lower alkyl wherein lower alkyl is straight or branched chainof 1 to 4 carbons.

R₈ is ##STR73## wherein m is zero, one, or two and R₁₃ is hydrogen,methyl, methoxy, methylthio, chloro, bromo, fluoro, or hydroxy.

R₈ is --S--lower alkyl wherein lower alkyl is straight or branched chainof 1 to 4 carbons.

R₈ is ##STR74## wherein m is zero, one or two and R₁₃ is hydrogen,methyl, methoxy, methylthio, chloro, bromo, fluoro or hydroxy.

R₉ is phenyl, 2-hydroxyphenyl, or 4-hydroxyphenyl.

R₁₀ are both fluoro or chloro.

R₁₀ are both --Y--R₁₆ wherein Y is O or S, R₁₆ is straight or branchedchain lower alkyl of 1 to 4 carbons or the R₁₆ groups join to completean unsubstituted 5- or 6-membered ring or said ring in which one or moreof the available carbons has a methyl or dimethyl substituent.

R₁₁, R'₁₁, R₁₂ and R'₁₂ are all hydrogen, or R₁₁ is phenyl,2-hydroxyphenyl, or 4-hydroxyphenyl and R'₁₁, R₁₂ and R'₁₂ are hydrogen.

R₂₄ is phenyl.

Most preferred compounds of this invention with respect to the peptidepart of the structure of formula I are those wherein: ##STR75##

R is hydrogen or methyl.

R₁ is hydrogen, methyl, or --(CH₂)--₄ NH₂.

R₆ is hydrogen, straight or branched chain lower alkyl of 1 to 4carbons, or an alkali metal salt.

R₄ is cyclohexyl or phenyl and R₅ is hydrogen.

R₄ is hydrogen and R₅ is methyl, --CH₂ --CH(CH₃)₂, ##STR76##

R₇ is hydrogen, cyclohexyl, lower alkoxy of 1 to 4 carbons, ##STR77##wherein m is zero, one, or two and R₁₃ is hydrogen, methyl, methoxy,methylthio, Cl, Br, F, or hydroxy, especially preferred wherein R₇ ishydrogen.

t is two or three, especially where t is two.

Preferred compounds of this invention with respect to the thiolsubstituted portion of the structure of formula I are those wherein:

R₂ is ##STR78## wherein m is zero, one, or two and R₁₄ is hydrogen,methyl, methoxy, methylthio, Cl, Br, F, or hydroxy, especially phenyl.

R₃ is straight or branched chain lower alkyl of 1 to 4 carbons,--(CH₂)_(r) --NH₂, ##STR79## wherein m is zero, one, or two, R₁₄ ishydrogen,methyl, methoxy, methylthio, Cl, Br, F, or hydroxy, and r is aninteger from 1 to 4, especially benzyl.

The compounds of formula I wherein R₆ is hydrogen form salts with avariety of inorganic or organic bases. The nontoxic, pharmaceuticallyacceptable salts are preferred, although other salts are also useful inisolating or purifying the product. Such pharmaceutically acceptablesalts include metal salts such as sodium, potassium or lithium, alkalineearth metal salts such as calcium or magnesium, and salts derived fromamino acids such as arginine, lysine, etc. The salts are obtained byreacting the acid form of the compound with an equivalent of the basesupplying the desired ion in a medium in which the salt precipitates orin aqueous medium and then lyophilizing.

Similarly, the compounds of formula I form salts with a variety ofinorganic and organic acids. Again, the non-toxic pharmaceuticallyacceptable salts are preferred, although other salts are also useful inisolating or purifying the product. Such pharmaceutically acceptablesalts include those formed with hydrochloric acid, methanesulfonic acid,sulfuric acid, maleic acid, etc. The salts are obtained by reacting theproduct with an equivalent amount of the acid in a medium in which thesalt precipitates.

As shown above, the peptide portion of the molecule of the products offormula I represented by ##STR80## is in the L-configuration (R₁ isother than hydrogen). One or two asymmetric centers are also present inthe thiol substituted portion of the molecule as represented by the * informula I. Of course, if R₃ is hydrogen, then only one center ispresent. Thus, the compounds of formula I can exist indiastereoisometric forms or in mixtures thereof. The above describedprocesses can utilize racemates, enantiomers or diastereomers asstarting materials. When diastereomeric products are prepared, they canbe separated by conventional chromatographic or fractionalcrystallization methods.

The products of formula I wherein the imino acid ring is monosubstitutedgive rise to cistrans isomerism. The configuration of the final productwill depend upon the configuration of the R₇, R₈ and R₉ substituent inthe starting material of formula XIV.

The compounds of formula I, and the pharmaceutically acceptable saltsthereof, are hypotensive agents. They inhibit the conversion of thedecapeptide angiotensin I to angiotensin II and, therefore, are usefulin reducing or relieving angiotensin related hypertension. The action ofthe enzyme renin on angiotensinogen, a pseudoglubulin in blood plasma,produces angiotensin I. Angiotensin I is converted by angiotensinconverting enzyme (ACE) to angiotensin II. The latter is an activepressor substance which has been implicated as the causative agent inseveral forms of hypertension in various mammalian species, e.g.,humans. The compounds of this invention intervene in theangiotensinogen→(renin)→angiotensin I→angiotensin II sequence byinhibiting angiotensin converting enzyme and reducing or eliminating theformation of the pressor substance angiotensin II. Thus by theadministration of a composition containing one (or a combination) of thecompounds of this invention, angiotensin dependent hypertension in aspecies of mammal (e.g., humans) suffering therefrom is alleviated. Asingle dose, or preferably two to four divided daily doses, provided ona basis of about 0.1 to 100 mg., preferably about 1 to 50 mg., per kg.of body weight per day is appropriate to reduce blood pressure. Thesubstance is preferably administered orally, but parenteral routes suchas the subcutaneous, intramuscular, intravenous or intraperitonealroutes can also be employed.

The compounds of this invention can also be formulated in combinationwith a diuretic for the treatment of hypertension. A combination productcomprising a compound of this invention and a diuretic can beadministered in an effective amount which comprises a total daily dosageof about 30 to 600 mg., preferably about 30 to 330 mg. of a compound ofthis invention, and about 15 to 300 mg., preferably about 15 to 200 mg.of the diuretic, to a mammalian species in need thereof. Exemplary ofthe diuretics contemplated for use in combination with a compound ofthis invention are the thiazide diuretics, e.g., chlorothiazide,hydrochlorothiazide, flumethiazide, hydroflumethiazide,bendroflumethiazide, methyclothiazide, trichloromethiazide, polythiazideor benzthiazide as well as ethacrynic acid, ticrynafen, chlorthalidone,furosemide, musolimine, bumetanide, triamterene, amiloride andspironolactone and salts of such compounds.

The compounds of formula I can be formulated for use in the reduction ofblood pressure in compositions such as tablets, capsules or elixirs fororal administration, or in sterile solutions or suspensions forparenteral administration. About 10 to 500 mg. of a compound of formulaI is compounded with physiologically acceptable vehicle, carrier,excipient, binder, preservative, stabilizer, flavor, etc., in a unitdosage form as called for by accepted pharmaceutical practice. Theamount of active substance in these compositions or preparations is suchthat a suitable dosage in the range indicated is obtained.

The compounds of formula I wherein X is ##STR81## also possessenkephalinase inhibition activity and are useful as analgesic agents.Thus, by the administration of a composition containing one or acombination of such compounds of formula I or a pharmaceuticallyacceptable salt thereof, pain is alleviated in the mammalian host. Asingle dose, or preferably two to four divided daily doses, provided ona basis of about 0.1 to about 100 mg. per kilogram of body weight perday, preferably about 1 to about 50 mg. per kilogram per day, producesthe desired analgesic activity. The composition is preferablyadministered orally but parenteral routes such as subcutaneous can alsobe employed.

The following examples are illustrative of the invention. Temperaturesare given in degrees centigrade. LH-B 20 refers to a Sephadexchromatography gel commercially available from Pharmacia Fine Chemicals.

EXAMPLE 11-[N-[(3S)-3-(Benzoylamino)-2-mercapto-4-phenylbutyl]-L-alanyl]-L-proline(isomer A) (a) (4-Methoxyphenyl)methyl disulfide

A benzene solution of iodine is added to a stirred mixture of4-methoxybenzenemethanethiol (25 g., 0.162 mole) in benzene (300 ml.)and water (300 ml.) containing sodium bicarbonate (29.4 g., 0.35 mole)until the color of iodine persists. After stirring for 15 minutes, theexcess iodine is quenched with sodium thiosulfate. The benzene fractionis washed with water, aqueous sodium thiosulfate, 1N sodium bicarbonate,and brine. After drying over anhydrous MgSO₄, the solvent is removed atreduced pressure to give a brown solid that is washed with ether to givea light tan solid. This material is dissolved in hot ethyl acetate forrecrystallization and while cooling the colorless solution turns darkbrown which is indicative of iodine. The resulting solution is cooled inan ice bath and the resulting solid is collected by filtration. Thissolid is then recrystallized from ethyl acetate and washed with ether togive 15.1 g. of (4-methoxyphenyl)methyl disulfide as a colorless solid;m.p. 98°-100°.

Anal. calc'd. for C₁₆ H₁₈ O₂ S₂ : C, 62.71; H, 5.92; S, 20.92. Found: C,62.60; H, 5.97; S, 20.86.

(b) (S)-3-[(Benzyloxycarbonyl)amino]-1-diazo-4-phenyl-2-butanone

Isobutyl chloroformate (23.4 ml., 180 mmole) is added to a solution ofN-benzyloxycarbonyl-L-phenylalanine (53.9 g., 180 mmole) andN-methylmorpholine (19.8 ml., 180 mmole) in dry tetrahydrofuran (250ml.) at -20° under argon. After stirring for 15 minutes, theN-methylmorpholine hydrochloride is removed by filtration and thefiltrate is treated with a cold (0°), etheral solution of diazomethane.The resulting mixture is allowed to warm to room temperature and stirredfor 2 hours. The excess diazomethane is removed by bubbling a stream ofnitrogen through the reaction mixture for 30 minutes. The solvent isremoved at reduced pressure and the residue is dissolved in ethylacetate. The resulting solution is washed with water (twice), 1N sodiumbicarbonate (twice), 0.25M citric acid (twice), and brine. After dryingover anhydrous MgSO₄, the solvent is removed at reduced pressure and theresidue is dissolved in isopropyl ether. The resulting precipitate iscollected by filtration to give 41.07 g. of(S)-3-[(benzyloxycarbonyl)amino]-1-diazo-4-phenyl- 2-butanone as a lightyellow solid. TLC(silica gel, hexane:ethyl acetate; (3:1) R_(f) =0.12.

(c) (S)-β-[(Benzyloxycarbonyl)amino]-benzenebutanoic acid, methyl ester

To a solution of(S)-3-[(benzyloxycarbonyl)amino]-1-diazo-4-phenyl-2-butanone (10 g.,30.8 mmole) in methanol (100 ml.) is added 0.5 ml. of a solution ofsilver benzoate (1.0 g.) in triethylamine (12.5 ml.). After nitrogenevolution ceases, an additional 0.5 ml. of the silverbenzoate/triethylamine solution is added and stirring continued for anadditional 15 minutes. The reaction mixture is treated with activatedcharcoal and filtered through Celite. The filtrate is concentrated atreduced pressure and the residue is dissolved in ethyl acetate. Thissolution is washed with water, 1N hydrochloric acid, 1N sodiumbicarbonate (twice), and brine. After drying over anhydrous MgSO₄, thesolvent is removed at reduced pressure and the residue ischromatographed (Florisil, ether) to give 9.43 g. of(S)-β-[(benzyloxycarbonyl)amino]-benzenebutanoic acid, methyl ester as awaxy yellow solid. TLC (silica gel; hexane:ethyl acetate; 4:1) R_(f)=0.25.

(d) (S)-β-(Benzoylamino)-benzenebutanoic acid, methyl ester

A mixture of (S)-β-[(benzyloxycarbonyl)amino]-benzenebutanoic acid,methyl ester (10.0 g., 30.5 mmole), p-toluenesulfonic acid monohydrate(5.8 g., 30.5 mmole), and palladium hydroxide carbon catalyst (1.0 g.)in 95% ethanol (170 ml.) is stirred under a hydrogen atmosphere(balloon). The system is evacuated and refilled with fresh hydrogenevery 20 minutes. After 1.5 hours, the catalyst is removed by filtrationand the filtrate is concentrated at reduced pressure to give a colorlesssolid.

To a solution of the above colorless solid and diisopropylethylamine(8.23 ml., 47.2 mmole) in anhydrous tetrahydrofuran (150 ml.) at 0° isadded benzoyl chloride (6.27 ml., 54 mmole). After stirring for 30minutes, the mixture is warmed to room temperature and stirringcontinued for 45 minutes. The reaction mixture is then treated with 1Nsodium bicarbonate (150 ml.). After stirring for 30 minutes, the bulk ofthe tetrahydrofuran is removed at reduced pressure and the residue isextracted with ethyl acetate. The ethyl acetate fraction is washed withwater (twice), 1N hydrochloric acid (twice), 1N sodium bicarbonate(twice), and brine. After drying over anhydrous MgSO₄, the solvent isremoved at reduced pressure and the residue is washed with hexane togive 8.15 g. of (S)-β-(benzoylamino)-benzenebutanoic acid, methyl esteras a colorless solid. TLC (silica gel; hexane:ethyl acetate, 1:1) R_(f)=0.38.

(e)(S)-β-(Benzoylamino)-α-[[(4-methoxyphenyl)methyl]thio]-benzenebutanoicacid, methyl ester

To a solution of freshly distilled diisopropylamine (2.07 ml., 14.8mmole) in dry tetrahydrofuran (20 ml.) at 0° under argon is added ahexane solution of n-butyl lithium (6.02 ml. of a 2.4M solution, 14.5mmole). After stirring at 0° for 30 minutes, the resulting solution oflithium diisopropylamide is cooled to -78° and a solution of(S)-β-(benzoylamino)-benzenebutanoic acid, methyl ester (2.0 g., 6.72mmole) in tetrahydrofuran (20 ml.) is added dropwise over a period of 5minutes. After stirring at -78° for 15 minutes, a solution of(4-methoxyphenyl)methyl disulfide (2.5 g., 8.07 mmole) intetrahydrofuran (9 ml.) is added. After 5 minutes at -78°, the mixtureis warmed to 0° and stirring continued for 45 minutes. The reaction isquenched with 1N hydrochloric acid and diluted with ethyl acetate. Theresulting solution is washed with water, 1N hydrochloric acid, 1N sodiumbicarbonate, and brine. After drying over anhydrous MgSO₄, the solventis removed at reduced pressure and the residue is flash chromatographed(silica gel LPS-1; benzene:ethyl acetate, 93:7) to give 1.85 g. of paleyellow solid(S)-β-(benzoylamino)-α-[[(4-methoxyphenyl)methyl]thio]-benzenebutanoicacid, methyl ester as a mixture of diastereomers. TLC (silica gel;benzene:ethyl acetate, 9:1) R_(f) =0.29 and 0.26.

(f)(S)-β-(Benzoylamino)-α-[[(4-methoxyphenyl)methyl]thio]-benzenebutanol(isomer A)

Lithium chloride (0.7 g., 4 eq.) and sodium borohydride (0.62 g., 4 eq.)are added to a solution of(S)-β-(benzoylamino)-α-[[(4-methoxyphenyl)methyl]thio]-benzenebutanoicacid, methyl ester (1.85 g., 4.11 mmole) in tetrahydrofuran (25 ml.) andabsolute ethanol (25 ml.). After stirring at room temperature for 21hours, the mixture is quenched with 1N hydrochloric acid and dilutedwith ethyl acetate. The resulting solution is washed with water, 1Nhydrochloric acid, 1N sodium bicarbonate, and brine. After drying overanhydrous MgSO₄, the solvent is removed at reduced pressure and theresidue flash chromatographed (silica gel LPS-1; benzene:acetone, 91:9)to give the separated diastereomers of(S)-β-(benzoylamino)-α-[[(4-methoxyphenyl)methyl]thio]-benzenebutanol ascolorless solids. Isomer A; 0.48 g.; TLC (silica gel; benzene:acetone,9:1) R_(f) =0.27; and isomer B; 0.52 g.; TLC (silica gel;benzene:acetone, 9:1) R_(f) =0.16.

(g)(S)-β-(Benzoylamino)-α-[[(4-methoxyphenyl)methyl]thio]-benzenebutanal(isomer A)

A mixture of anhydrous dimethylsulfoxide (5 ml.) andpyridinium-1-sulfonate (0.91 g., 5.65 ml.) at room temperature underargon is stirred for 15 minutes and then diluted with dry methylenechloride (5 ml.). To the resulting solution is added a solution of(S)-β-(benzoylamino)-α-[[(4-methoxyphenyl)methyl]thio]-benzenebutanol(isomer A) (0.48 g., 1.13 mmole) and diisopropylethylamine (1.98 ml.,11.3 mmole) in methylene chloride (7 ml.). After stirring for 15minutes, the mixture is diluted with ethyl acetate and washed with water(twice), 1N sodium bicarbonate (twice), and brine. After drying overanhydrous MgSO₄, the solvent is removed at reduced pressure to give 0.45g. of(S)-β-(benzoylamino)-α-[[(4-methoxyphenyl]methyl]thio]-benzenebutanal(isomer A) as a pale yellow solid. TLC (silica gel; benzene:acetone,9:1) R_(f) =0.44.

(h)1-[N-[(3S)-3-(Benzoylamino)-2-[[(4-methoxyphenyl)methyl]thio]-4-phenylbutyl]-L-alanyl]-L-proline,1,1-dimethylethyl ester (isomer A)

A mixture of(S)-β-(benzoylamino)-α-[[(4-methoxyphenyl)methyl]thio]-benzenebutanal(isomer A) (0.45 g., 1.07 mmole), L-alanyl-L-proline, 1,1-dimethylethylester (0.78 g., 3.21 mmole), and crushed 3A° molecular sieves (2 g.) intetrahydrofuran (5 ml.) and absolute ethanol (5 ml.) is stirred at roomtemperature under argon. After 2.5 hours, sodium cyanoborohydride (0.20g., 3 eq.) is added and stirring continued for 15 hours. The reactionmixture is filtered to remove the sieves and the filtrate is dilutedwith ethyl acetate and washed with water, 1N hydrochloric acid (twice),1N sodium bicarbonate, and brine. After drying over anhydrous MgSO₄, thesolvent is removed to give the desired product, as a mixture ofdiastereomers, as a pale yellow oil. TLC (silica gel, benzene:acetone,4:1) isomer A at R_(f) =0.30 and isomer B at R_(f) =0.13. Flashchromatography (silica gel LPS-1; benzene:acetone, 7:3) affords impureproduct (isomer A). Repeated flash chromatography (silica gel LPS-1;ethyl acetate:benzene, 6:4) gives 0.20 g. of1-[N-[(3S)-3-(benzoylamino)-2-[[(4-methoxyphenyl)methyl]thio]-4-phenylbutyl]-L-alanyl]-L-proline,1,1-dimethylethyl ester (isomer A) as a nearly colorless oil.

(i)1-[N-[(3S)-3-(Benzoylamino)-2-mercapto-4-phenylbutyl]-L-alanyl]-L-proline(isomer A)

A solution of the 1,1-dimethylethyl ester product from part (h) (0.57g., 0.88 mmole) and anisole (1.0 ml.) in trifluoroacetic acid (19 ml.)is stirred at room temperature for 1 hour. After cooling to 0°, mercurictrifluoroacetate (376 mg., 0.88 mmole) is added. After stirring for 1hour, the bulk of the trifluoroacetic acid is removed at reducedpressure. The residue is treated with ether to afford a colorless solidwhich is collected by filtration (535 mg.).

The above solid (535 mg.) is dissolved in 80% acetic acid (20 ml.) andhydrogen sulfide is bubbled through the solution for 30 minutes. Theresulting black mercuric sulfide is removed by filtration throughCelite. The filtrate is refiltered through a Teflon millipore filter andconcentrated at reduced pressure. The residue is chased twice withabsolute ethanol, dissolved in water (8 ml.), treated with 1Nhydrochloric acid (0.5 ml.), and lyophilized to give 0.33 g. of1-[N-[(3S)-3-(benzoylamino)-2-mercapto-4-phenylbutyl]-L-alanyl]-L-proline(isomer A) as a colorless solid; m.p. 142°-176° (dec.); [α]_(D) ²⁰=-89.6° (c=1.07, methanol). TLC (silica gel, n-butanol:aceticacid:water, 4:1:1) R_(f) =0.50.

Anal. calc'd. for C₂₅ H₃₁ N₃ O₄ S.HCl.0.38H₂ O: C, 58.54; H, 6.44; N,8.19; Cl, 6.91; S, 6.25; SH, 6.45. Found: C, 58.54; H, 6.44; N, 8.15;Cl, 6.91; S, 6.15; SH, 6.26.

EXAMPLE 21-[N-[(3S)-3-(Benzoylamino)-2-mercapto-4-phenylbutyl]-L-alanyl]-L-proline,monohydrochloride (isomer B) (a)1-[N-[(3S)-3-(Benzoylamino)-2-[[(4-methoxyphenyl)methyl]thio]-4-phenylbutyl]-L-alanyl]-L-proline,1,1-dimethylethyl ester (isomer B)

The partially purified mixture of diastereomers from Example 1(h), inwhich isomer B is the major component, is rechromatographed (flash,silica gel LPS-1; chloroform:methanol, 99:1) to give 0.26 g. of1-[N-[(3S)-3-(benzoylamino)-2-[[(4-methoxyphenyl)methyl]thio]-4-phenylbutyl]-L-alanyl]-L-proline,1,1-dimethylethyl ester (isomer B) as a colorless oil. TLC (silica gel;chloroform:methanol, 96:4) R_(f) =0.28.

(b)1-[N-[(3S)-3-(Benzoylamino)-2-mercapto-4-phenylbutyl]-L-alanyl]-L-proline,monohydrochloride (isomer B)

A solution of the 1,1-dimethylethyl ester product from part (a) (0.26g., 0.40 mmole) and anisole (0.5 ml.) in trifluoroacetic acid (9.5 ml.)is stirred at room temperature for one hour. After cooling to 0°,mercuric trifluoroacetate (171 mg., 1 eq.) is added. After stirring for45 minutes, the bulk of the trifluoroacetic acid is removed at reducedpressure. The residue is treated with ether to give a colorless productwhich is collected by filtration (260 mg.).

The above colorless solid (260 mg.) is dissolved in 80% acetic acid (10ml.) and hydrogen sulfide is bubbled through this solution for 30minutes. The resulting black mercuric sulfide is removed by filtrationthrough Celite. The product is refiltered (Teflon millipore) and thefiltrate is concentrated at reduced pressure. The residue is chased oncewith absolute ethanol, dissolved in water (10 ml.), and then treatedwith 1N hydrochloric acid. The resulting solution is lyophilized to givea white fluffy solid (150 mg.). This material is dissolved in water (9ml.), filtered (Teflon millipore), and relyophilized to a white fluffysolid which is then dried under vacuum over phosphorus pentoxide to give136 mg. of1-[N-[(3S)-3-(benzoylamino)-2-mercapto-4-phenylbutyl]-L-alanyl]-L-proline,monohydrochloride (isomer B); m.p. 147°-162°; [α]_(D) ²⁰ =-64.5°(c=1.06, methanol). TLC (silica gel; n-butanol:acetic acid:water, 4:1:1)R_(f) =0.47.

Anal. calc'd. for C₂₅ H₃₁ N₃ O₄ S.HCl.0.36 H₂ O: C, 58.58; H, 6.44; N,8.20; S, 6.25; Cl, 6.92; SH, 6.45. Found: C, 58.58; H, 6.50; N, 8.14; S,6.15; Cl, 6.71; SH, 6.10.

EXAMPLE 3 1-[N-[(3S)-3-(Benzoylamino)-2-mercapto-4-phenylbutyl]-L-lysyl]-L-proline, monohydrochloride (isomer A) (a) 1-[N²-[(Benzyloxy)carbonyl]-N⁶-[(1,1-dimethylethoxy)carbonyl]-L-lysyl]-L-proline, 1,1-dimethylethylester

A suspension of N² -[(benzyloxy)carbonyl]-N⁶-[(1,1-dimethylethoxy)carbonyl]-L-lysine, dicyclohexylamine salt (10.0g., 17.8 mmole) in ethyl acetate (300 ml.) is extracted with 1Nhydrochloric acid (three times). The organic phase is then washed withwater and brine. After drying over anhydrous MgSO₄, the solvent isremoved to give 5.81 g. of N² -[(benzyloxy)carbonyl]-N⁶-[(1,1-dimethylethoxy)carbonyl]-L-lysine as a pale yellow oil.

To a solution of N² -[(benzyloxy)carbonyl]-N⁶-[(1,1-dimethylethoxy)carbonyl]-L-lysine (5.81 g., 15.3 mmole) andL-proline, 1,1-dimethylethyl ester (2.80 g., 16.4 mmole) in drymethylene chloride (70 ml.) is added 1-hydroxybenzotriazole (2.02 g.,14.95 mmole) and dicyclohexylcarboiimide (3.09 g., 14.98 mmole). Afterstirring at room temperature for 15 hours, the mixture is filtered toremove the dicyclohexylurea. The filtrate is concentrated at reducedpressure and the residue is dissolved in ether and refiltered. Thefiltrate is washed with water (twice), 1N hydrochloric acid (twice), 1Nsodium bicarbonate, and brine. After drying over anhydrous MgSO₄, thesolvent is removed at reduced pressure and the residue is flashchromatographed (silica gel LPS-1; hexane:ethyl acetate, 1:1) to give8.13 g. of 1-[N² -[(benzyloxy)carbonyl]-N⁶-[(1,1-dimethylethoxy)carbonyl]-L-lysyl]-L-proline, 1,1-dimethylethylester as a colorless oil. TLC (silca gel; hexane:ethyl acetate, 1:1)R_(f) =0.21.

(b) 1 -[N⁶ -[(1,1-Dimethylethoxy)carbonyl]-L-lysyl]-L-proline,1,1-dimethylethyl ester

A mixture of the 1,1-dimethylethyl ester product from part (a) (4.13 g.,7.73 mmole) and palladium hydroxide/carbon catalyst (400 mg.) in ethylacetate (90 ml.) and ethanol (10 ml.) is stirred under a hydrogenatmosphere (balloon). The system is evacuated and refilled with freshhydrogen every 30 minutes. After stirring for 3 hours, the catalyst isremoved by filtration (Teflon millipore) and the filtrate isconcentrated at reduced pressure to give 3.15 g. of 1-[N⁶-[(1,1-dimethylethoxy)carbonyl]-L-lysyl]-L-proline, 1,1-dimethylethylester as a colorless solid.

(c)1-[N-[(3S)-3-(Benzoylamino)-2-[[(4-methoxyphenyl]methyl]thio]-4-phenylbutyl]-N⁶-[(1,1-dimethylethoxy)carbonyl]-L-lysyl]-L-proline, 1,1-dimethylethylester (isomer A)

A mixture of(S)-β-(benzoylamino)-α-[[(4-methoxyphenyl)methyl]thio]-benzenebutanal(isomer A) (0.59 g. 1.40 mmole), 1-[N⁶-[(1,1-dimethylethoxy)carbonyl]-L-lysyl]-L-proline, 1,1-dimethylethylester (1.55 g., 3.88 mmole), and crushed 3 A° molecular sieves (2.0 g.)in tetrahydrofuran (5 ml.) and absolute ethanol (5 ml.) is stirred atroom temperature under argon. After stirring for 2 hours, sodiumcyanoborohydride (0.27 g., 3 eq.) is added and stirring continued for 18hours. The reaction mixture is filtered through Celite to remove thesieves. The filtrate is then diluted with ethyl acetate and washed withwater, 1N hydrochloric acid (twice), 1N sodium bicarbonate, and brine.After drying over anhydrous MgSO₄, the solvent is removed at reducedpressure to give the desired product, a mixture of diastereomers, as apale yellow oil. TLC (silica gel, benzene:acetone 4:1) isomer A at R_(f)=0.31, and isomer B at R_(f) =0.15. Repeated chromatography (flash,silica gel LPS-1; chloroform:methanol, 98:2; hexane-acetone, 65:35;benzene:acetone, 4:1; ethyl acetate:hexane, 6:4; ethyl acetate:hexane,6:4) gives 0.41 g. of1-[N-[(3S)-3-(benzoylamino)-2-[[(4-methoxyphenyl)methyl]thio]-4-phenylbutyl]-N⁶-[(1,1-dimethylethoxy)carbonyl]-L-lysyl]-L-proline, 1,1-dimethylethylester (isomer A) as a colorless oil.

(d)1-[N-[(3S)-3-(Benzoylamino)-2-mercapto-4-phenylbutyl]-L-lysyl]-L-proline,monohydrochloride (isomer A)

A solution of the 1,1-dimethylethyl ester product from part (c) (0.41g., 0.51 mmole) and anisole (0.6 ml.) in trifluoroacetic acid (12 ml.)is stirred at room temperature for one hour. After cooling to 0°,mercuric trifluoroacetate (217 mg., 1.0 eq.) is added. After stirringfor one hour at 0°, the bulk of the trifluoroacetic acid is removed atreduced pressure. The residue is treated with ether to give a colorlesssolid which is collected by filtration (0.49 g.).

This solid (0.49 g.) is dissolved in 80% acetic acid (17 ml.) andhydrogen sulfide is bubbled through the solution for 30 minutes. Theresulting black mercuric sulfide is removed by filtration throughCelite. The filtrate is refiltered (Teflon millipore) and thenconcentrated at reduced pressure. The residue is dissolved in water (10ml.) and treated with 1N hydrochloric acid (1.5 ml.) and thenlyophilized. The material is redissolved in water containing a smallamount of hydrochloric acid and relyophilized. The material is finallylyophilized from water to give 290 mg. of1-[N-[(3S)-3-(benzoylamino)-2-mercapto-4-phenylbutyl]-L-lysyl]-L-proline,monohydrochloride (isomer A); m.p. 157°-180°; [α]_(D) ²⁰ =-60.0°(c=1.15, methanol). TLC (silica gel; n-butanol:acetic acid:water, 4:1:1)R_(f) =0.16.

Anal.calc'd. for C₂₈ H₃₈ N₄ O₄ S.2HCl.1.0H₂ O: C, 54.45; H, 6.85; N,9.07, S, 5.19; Cl, 11.48; SH, 5.35. Found: C, 54.35; H, 6.67; N, 8.97;S, 5.20 Cl, 11.36; SH, 5.23.

EXAMPLES 4-42

Following the procedure of Examples 1 to 3 the carboxylic acid methylester shown in Col. I is reacted with (4-methoxyphenyl)methyl disulfideto yield the carboxylic acid methyl ester shown in Col. II. This is thenconverted to the corresponding alcohol and then the aldehyde shown inCol. III. The aldehyde is then reacted with the peptidyl ester shown inCol. IV to yield the protected sulfide product shown in Col. V. Removalof the S-protecting group and the carboxylic acid ester group yields thefinal product shown in Col. VI. ##STR82##

      Example R.sub.3 R.sub.2 R.sub.1 X R             4      ##STR83##      H      ##STR84##      H.sub.3 C      5     ##STR85##      ##STR86##      H      ##STR87##      H.sub.3 C  6 H.sub.3      C     ##STR88##      ##STR89##      ##STR90##      H      7     ##STR91##      ##STR92##      H.sub.3      C     ##STR93##      H      8     ##STR94##      ##STR95##      H      ##STR96##      ##STR97##      9     ##STR98##      ##STR99##      H      ##STR100##      ##STR101##      10     ##STR102##      ##STR103##      H      ##STR104##      H.sub.3 C      11     ##STR105##      ##STR106##      H.sub.3      C     ##STR107##      H.sub.3 C      12     ##STR108##      ##STR109##      H.sub.3      C     ##STR110##      H      13     ##STR111##      ##STR112##      H.sub.3      C     ##STR113##      H      14     ##STR114##      ##STR115##      H      ##STR116##      H.sub.3 C      15     ##STR117##      ##STR118##      H.sub.3      C     ##STR119##      H      16     ##STR120##      ##STR121##      H.sub.3      C     ##STR122##      H      17     ##STR123##      ##STR124##      H.sub.3      C     ##STR125##      H  18 H.sub.3      C     ##STR126##      ##STR127##      ##STR128##      H      19     ##STR129##      ##STR130##      H      ##STR131##      H  20 H.sub.3      CCH.sub.2     ##STR132##      ##STR133##      ##STR134##      H      21     ##STR135##      ##STR136##      ##STR137##      ##STR138##      H      22     ##STR139##      ##STR140##      ##STR141##      ##STR142##      H      23     ##STR143##      ##STR144##      ##STR145##      ##STR146##      H      24     ##STR147##      ##STR148##      ##STR149##      ##STR150##      H      25     ##STR151##      ##STR152##      ##STR153##      ##STR154##      H      26     ##STR155##      ##STR156##      ##STR157##      ##STR158##      H      27     ##STR159##      ##STR160##      ##STR161##      ##STR162##      H      28     ##STR163##      ##STR164##      H.sub.3 CS(H.sub.2      C).sub.2     ##STR165##      H      29     ##STR166##      ##STR167##      H.sub.3      C     ##STR168##      H      30     ##STR169##      ##STR170##      H.sub.3      C     ##STR171##      H      31     ##STR172##      ##STR173##      H.sub.3      C     ##STR174##      H  32 H.sub.3      C     ##STR175##      H      ##STR176##      H.sub.3 C  33 H.sub.5      C.sub.2     ##STR177##      ##STR178##      ##STR179##      H  34 H.sub.3      C     ##STR180##      H.sub.3      C     ##STR181##      H  35 H.sub.3      C     ##STR182##      ##STR183##      ##STR184##      H  36 H.sub.3      C     ##STR185##      H.sub.3      C     ##STR186##      H      37     ##STR187##      ##STR188##       H.sub.3      C     ##STR189##      H      38     ##STR190##      ##STR191##      H.sub.3      C     ##STR192##      H      39     ##STR193##      ##STR194##      H      ##STR195##      H.sub.3 C      40     ##STR196##      ##STR197##      H.sub.3      C     ##STR198##      H      41     ##STR199##      ##STR200##      H      ##STR201##      H.sub.3 C      42     ##STR202##      ##STR203##      H.sub.3      C     ##STR204##      H

The R₁ protecting groups in Examples 20 to 26, the R₃ protecting groupin Example 29, and R₅ protecting group in Example 35 are removed as thelast step in the synthesis. The 4-azidoproline of Example 30 whentreated with the reducing agent will yield a 4-aminoproline product. TheR₆ ester groups shown in Examples 37 to 42 are not removed.

EXAMPLES 43-55

1-[N-[(3S)-3-(Benzoylamino)-2-[[(4-methoxyphenyl)-methyl]thio]-4-phenylbutyl]-L-alanyl]-L-proline(isomer A) is treated with the reagent listed below in Col. I to givethe product shown in Col. II. ##STR205## Deprotection by treatment withmercuric trifluoroacetate yields the desired final product.

    __________________________________________________________________________    Example                                                                            Col. I                 R.sub.6                                           __________________________________________________________________________    43                                                                                  ##STR206##                                                                                           ##STR207##                                       44                                                                                  ##STR208##                                                                                           ##STR209##                                       45                                                                                  ##STR210##                                                                                           ##STR211##                                       46                                                                                  ##STR212##                                                                                           ##STR213##                                       47                                                                                  ##STR214##                                                                                           ##STR215##                                       48                                                                                  ##STR216##                                                                                           ##STR217##                                       49                                                                                  ##STR218##                                                                                           ##STR219##                                       50                                                                                  ##STR220##            CH(CH.sub.2OH).sub.2                              51                                                                                  ##STR221##                                                                                           ##STR222##                                       52   HOCHCH.sub.2N(CH.sub.3).sub.2                                                                        CH.sub.2CH.sub.2N(CH.sub.3).sub.2                 53                                                                                  ##STR223##                                                                                           ##STR224##                                       54                                                                                  ##STR225##                                                                                           ##STR226##                                       55                                                                                  ##STR227##                                                                                           ##STR228##                                       __________________________________________________________________________

In the case of Examples 50 to 55, the reaction with the reagent listedin Col. I is performed in the presence of a coupling agent such asdicyclohexylcarbodiimide.

EXAMPLE 561-[N-[(3S)-3-(Benzoylamino)-2-mercapto-4-phenylbutyl]-L-ananyl]-L-proline,sodium salt (isomer A)

1-[N-[(3S)-3-(Benzoylamino)-2-mercapto-4-phenylbutyl]-L-alanyl]-L-proline(isomer A) (1 mmole) is dissolved in water (50 ml.). Aqueous sodiumbicarbonate (0.1N, 20 ml.) is added and the aqueous solution islyophilized. It is then dissolved in water (10 ml.) and applied on acolumn (5 cm.×60 cm.) of Sephadex chromatography gel G-10 and elutedwith water. Fractions containing the desired product are pooled andlyophilized to give1-[N-[(3S)-3-(benzoylamino)-2-mercapto-4-phenylbutyl]-L-alanyl]-L-proline,sodium salt (isomer A).

EXAMPLE 57

1000 tablets each containing the following ingredients

    ______________________________________                                        1-[N--[(3S)--3-(Benzoylamino)-                                                                        100    mg.                                            2-mercapto-4-phenylbutyl]-L-                                                  alanyl]-L-proline, sodium salt                                                (isomer A)                                                                    Corn starch             50     mg.                                            Gelatin                 7.5    mg.                                            Avicel (microcrystalline cellulose)                                                                   25     mg.                                            Magnesium stearate      2.5    mg.                                                                    185    mg.                                            ______________________________________                                    

are prepared from sufficient bulk quantities by mixing the1-[N-[(3S)-3-(benzoylamino)-2-mercapto-4-phenylbutyl]-L-alanyl]-L-proline,sodium salt (isomer A) and corn starch with an aqueous solution of thegelatin. The mixture is dried and ground to a fine powder. The Aviceland then the magnesium stearate are admixed with granulation. Thismixture is then compressed in a tablet press to form 1000 tablets eachcontaining 100 mg. of active ingredient.

In a similar manner, tablets containing 100 mg. of the product of any ofExamples 1 to 55 can be prepared.

A similar procedure can be employed to form tablets containing 50 mg. ofactive ingredient.

EXAMPLE 58

Two piece #1 gelatin capsules each containing 50 mg. of1-[N-[(3S)-3-(benzoylamino)-2-mercapto-4-phenylbutyl]-L-lysyl]-L-proline,monohydrochloride (isomer A) are filled with a mixture of the followingingredients:

    ______________________________________                                        1-[N--[(3S)--3-(benzoylamino)-                                                                        50     mg.                                            2-mercapto-4-phenylbutyl]-                                                    L-lysyl]-L-proline, monohydro-                                                chloride (isomer A)                                                           Magnesium stearate      7      mg.                                            Lactose                 193    mg.                                                                    250    mg.                                            ______________________________________                                    

In a similar manner capsules containing 50 mg. of the product of any ofExamples 1,2 and 4 to 56 can be prepared.

EXAMPLE 59

An injectable solution is prepared as follows:

    ______________________________________                                        1-[N--[(3S)--3-(Benzoylamino)-2-                                                                       500    g.                                            mercapto-4-phenylbutyl]-L-                                                    alanyl]-L-proline, sodium salt                                                (isomer A)                                                                    Methyl paraben           5      g.                                            Propyl paraben           1      g.                                            Sodium chloride          25     g.                                            Water for injection      5      l                                             ______________________________________                                    

The active substance, preservatives, and sodium chloride are dissolvedin 3 liters of water for injection and then the volume is brought up to5 liters. The solution is filtered through a sterile filter andaseptically filled into presterilized vials which are closes withpresterilized rubber closures. Each vial contains 5 ml. of solution in aconcentration of 100 mg. of active ingredient per ml. of solution forinjection.

In a similar manner, an injectable solution containing 100 mg. of activeingredient per ml. of solution can be prepared for the product of any ofExamples 1 to 56.

EXAMPLE 60

1000 tablets each containing the following ingredients:

    ______________________________________                                        1-[N--[(3S)--3-(Benzoylamino)-                                                                        100    mg.                                            2-mercapto-4-phenylbutyl]-L-                                                  alanyl]-L-proline, sodium salt                                                (isomer A)                                                                    Avicel                  100    mg.                                            Hydrochlorothiazide     12.5   mg.                                            Lactose                 113    mg.                                            Cornstarch              17.5   mg.                                            Stearic Acid            7      mg.                                                                    350    mg.                                            ______________________________________                                    

are prepared from sufficient bulk quantitites by slugging the1-[N-[(3S)-3-(benzoylamino)-2-mercapto-4-phenylbutyl]-L-alanyl]-L-proline,sodium salt (isomer A), Avicel, and a portion of the stearic acid. Theslugs are ground and passed through a #2 screen, then mixed with thehydrochlorothiazide, lactose, cornstarch, and remainder of the stearicacid. The mixture is compressed into 350 mg. capsule shaped tablets in atablet press. The tablets are scored for dividing in half.

In a similar manner, tablets can be prepared containing 100 mg. of theproduct of any of Examples 1 to 55.

What is claimed is:
 1. A compound of the formula ##STR229## wherein R₂is ##STR230## R₃ is hydrogen, lower alkyl, ##STR231## halo substitutedlower alkyl, --(CH₂)_(m) -cycloalkyl, ##STR232## --(CH₂)_(r) --OH,##STR233## --(CH₂)_(r) --NH₂, --(CH₂)_(r) --SH, --(CH₂)_(r) --S-loweralkyl, ##STR234## r is an integer from 1 to 4; R₁₄ is hydrogen, loweralkyl of 1 to 4 carbons, lower alkoxy of 1 to 4 carbons, lower alkylthioof 1 to 4 carbons, chloro, bromo, fluoro, trifluoromethyl, or hydroxy;mis zero, one, two, three, or four; and p is one, two or three providedthat p is more than one only if R₁₄ is hydrogen, methyl, methoxy,chloro, or fluoro.
 2. A compound of the formula ##STR235## wherein R₂ is##STR236## R₃ is hydrogen, lower alkyl, ##STR237## halo substitutedlower alkyl, --(CH₂)_(m) -cycloalkyl, ##STR238## --(CH₂)_(r) --OH,##STR239## --(CH₂)_(r) --NH₂, --(CH₂)_(r) --SH, --(CH₂)_(r) --S-loweralkyl, ##STR240## r is an integer from 1 to 4; R₁₄ is hydrogen, loweralkyl of 1 to 4 carbons, lower alkoxy of 1 to 4 carbons, lower alkylthioof 1 to 4 carbons, chloro, bromo, fluoro, trifluoromethyl, or hydroxy;mis zero, one, two, three, or four; and p is one, two or three providedthat p is more than one only if R₁₄ is hydrogen, methyl, methoxy,chloro, or fluoro.
 3. A compound of claim 1 wherein:R₂ is ##STR241## R₃is straight or branched chain lower alkyl of 1 to 4 carbons, --(CH₂)_(r)--NH₂, ##STR242## r is an integer from 1 to 4; R₁₄ is hydrogen, methyl,methoxy, methylthio, chloro, bromo, fluoro, or hydroxy; and m is zero,one, or two.
 4. The compound of claim 3 wherein:R₂ is phenyl; and R₃ is##STR243##
 5. A compound of claim 2 wherein:R₂ is ##STR244## R₃ isstraight or branched chain lower alkyl of 1 to 4 carbons, --(CH₂)_(r)--NH₂, ##STR245## r is an integer from 1 to 4; R₁₄ is hydrogen, methyl,methoxy, methylthio, chloro, bromo, fluoro, or hydroxy; and m is zero,one, or two.
 6. The compound of claim 5 wherein:R₂ is phenyl; and R₃ is##STR246##